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Decreased acid secretion and gastric lesion production by morphine in rats
Abstract:
The effects of graded doses of morphine on gastric secretion were studied in conscious rats with pyloric occlusion. It was found that, at doses which significantly prolonged the reaction time in the tail-immersion test, morphine significantly decreased both the volume and total acid output of gastric secretion. It was also observed that morphine produced gastric mucosal lesions in a dose-dependent manner. Pretreatment with naloxone 4 mg/kg significantly alleviated the gastric effects of morphine 32 mg/kg. It is suggested that the depressant effects of morphine on gastric secretion and the ulcerogenicity of the narcotic result from its stimulant activity on opiate receptors.
Insights
Morphine, at pain-relieving doses, reduces gastric secretion and causes stomach lesions in rats. Naloxone, an opiate antagonist, reversed these effects, suggesting opiate receptor involvement.
Area of Science:
- Pharmacology
- Gastroenterology
- Neuroscience
Background:
- Opioid analgesics like morphine are widely used for pain management.
- Morphine's effects on the gastrointestinal system, particularly gastric secretion and mucosal integrity, are not fully understood.
- Opiate receptors are known to play roles in various physiological processes, including pain and gastrointestinal function.
Purpose of the Study:
- To investigate the impact of graded doses of morphine on gastric secretion in conscious rats.
- To determine if morphine induces gastric mucosal lesions and if these effects are dose-dependent.
- To explore the role of opiate receptors in mediating morphine's effects on gastric function and ulcerogenicity.
Main Methods:
- Conscious rats underwent pyloric occlusion to collect gastric secretions.
- Graded doses of morphine were administered, and effects on gastric volume and acid output were measured.
- Gastric mucosal lesions were assessed in a dose-dependent manner.
- Rats were pretreated with naloxone (an opiate receptor antagonist) to evaluate its effect on morphine-induced gastric changes.
Main Results:
- Morphine significantly decreased gastric secretion volume and total acid output at doses that also prolonged reaction time in the tail-immersion test.
- Morphine administration resulted in dose-dependent gastric mucosal lesions.
- Pretreatment with naloxone (4 mg/kg) significantly alleviated the gastric effects induced by morphine (32 mg/kg).
Conclusions:
- Morphine exerts a dose-dependent inhibitory effect on gastric secretion in rats.
- Morphine exhibits ulcerogenic properties, inducing gastric mucosal lesions.
- The findings suggest that the effects of morphine on gastric secretion and its ulcerogenicity are mediated through stimulation of opiate receptors, as evidenced by naloxone's antagonistic action.